Wireless LAN systems, such as those based on the Institute of Electrical and Electronics Engineers (IEEE) Standard 802.11, for example, are packet-based communication systems, where the entire information to be conveyed from the transmitter to the receiver is encoded in a packet. The packet includes a preamble that is used for synchronization, a header that provides information about the contents of the data, and a payload that contains the information to be transmitted. In current wireless local area network (LAN) systems, the preamble, header, and payload are time-multiplexed in a packet and occupy the entire channel bandwidth for transmission and reception.
In an unscheduled mode of operation using carrier sense multiple access with collision avoidance (CSMA/CA), wireless LAN devices, namely stations (STA), continuously look for unpredictably arriving packets in the receive mode or continuously assess a clear channel to determine when the device can transmit if the channel is clear. This unscheduled mode of operation, referred to as “idle listening”, impacts power consumption due to the continuous scan for transmissions by the access point (AP) or other devices in the network. For large bandwidth systems (for example, gigahertz (GHz) of bandwidth), high-speed analog-to-digital converters (ADCs) are required for operation and can consume a significant portion of the idle listening mode power consumption.